Preload latch



J. E. HOGAN PRELOAD LATCH July 14, 1959 2 Sheets-Sheet 1 Filed Dec. 3,1956 jiu' w INVENTOR. JOHN 5/1064 grroe/vsrs J. E. HOGAN PRELOAD LATCHJuly 14, 1959 2 Sheets-Sheet 2 Filed Dec. s, 1956 INVENTOR.

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do/r/v 5/7004 oil-I a ATTae/ws'rs United States Patent PRELOAD LATCHJohn E. Hogan, Los Angeles, Calif., assignor to Clark Hartwell, LosAngeles, Calif., doing business under the fictitious name and style ofHartwell Aviation Supply Company Application December 3, 1956, SerialNo. 626,030

7 Claims. (Cl. 292-113) This invention relates to preload latches, thatis, to latches arranged to draw cooperating structures together with apredetermined initial load so as to eliminate relative movement of thestructures under intended conditions of operation.

Included in the objects of this invention are:

First, to provide a preload latch which is particularly arranged foreffecting end-to-end connection of component structures, and may bearranged for use in sets to join, for example, an instrument carrying nose-piece to the fuselage of an aircraft.

Second, to provide a preload latch wherein latch arms projecting fromone structure may be readily guided into engagement with a mating catchelement in the component structure, whereupon the two structures may bedrawn together and secured.

Third, to provide in a preload latch a novel means for controlling themovement of the catch element so as to move the catch element between aninoperative position free from interference with the mating latch, andan operative position holding the latch with predetermined tension.

' Fourth, to provide in a preload latch a novel, yieldably -mounted,latch element and means for guiding the latch element into propercatch-engaging position.

Fifth, to provide a preload latch which is provided with a manuallyoperable handle adapted to be folded into a position flush with thesurrounding structure in which the latch is mounted.

With the above :and other objects in view, as may appear hereinafter,reference is directed to the accompanying drawings in which:

Figure l is a top or plan view of preload latch, show ing the componentsthereof in their connected or latched position;

. Fig. 2 is a side view thereof, indicating fragmentarily by dottedlines the latch and latch hook;

Fig. 3 is an end view of one component of the latch which carries thelatch hook and operating mechanism;

- Fig. 4 is a separated-view of the latch components with the latchshown in itsopen position;

I Fig. 5 is an enlarged longitudinal sectional view taken through 5-5 ofFig. l;

Fig.' 6 is a fragmentary, partial elevational, partial longitudinal,sectional .vieW, similar to Fig. 5 but showing the parts of the latchstructure in its open position;

Fig.7 is a sectional view through 77 of Fig. 5, showing the parts of thelatch in its closed position.

' The preload latch includes a housing member 1 having a central channelportion 2 of rectangular cross section to form verticalside walls .3 anda bottom wall 4. The upper edges of the side walls are provided withlaterally extending flanges 5 which are contoured so that the upper.side of the housing member 1 may be mounted flush in a surroundingstructure, for example, an airplane fuselage, wing, or appendage.

" The ends of the channel portion 2 are closed. One

end is closed by an apron 6 which projects beyond the boundaries of thechannel portion 2 and is adapted for flush mounting in the end of thestructure in which the housing 1 is mounted. The apron is provided witha centering aperture 7 communicating with the channel 2. The centeringaperture is provided with tapering side walls.

Mounted within the channel 2 is a latch hook or catch member 8 having ahook end 9. The catch member is suspended within the channel 2 by meansof forward suspension arms 10 connected to the catch member 3 by a shaft11. The suspension arms 10 are also provided with journal pins 12 whichextend laterally through journal bosses provided in the side walls 3 ofthe channel 2.

The catch member 8 extends rearwardly of the suspension arms 10 and isjoined to a rearward suspension arm 13 by means of a journal pin 14.The'suspension arm 13 is j-ournaled relative to the housing 1 on a shaft15 which extends through the side walls 3 and is provided with bushings16 for centering the suspension arm 13 in the channel 2. p

The pivotal connections of the forward suspension arms 10 and rearwardsuspension arm 13 with the side Walls 3 are located above their'pivotalconnections with the catch member 8. Furthermore, the suspension arm 13is longer than the suspension arms 10; consequently, the hook member iscapable of a forward and rearward movement which also results in upwarddisplacement of the hook end 9 as the catch member 8 moves forward. Thismovement is utilized to move the hook end 9 of the catch member 8 freeof the mating latch member, as Will be described hereinafter.

Also mounted on the shaft 11 are connecting bars 17 which extendforwardly and are connected by journal pins 18 to a U-shaped yoke lever19 located'near the forward extremity of the housing 1, that is,adjacent and above the centering aperture 7. The legs of the yoke lever19 are located contiguous to the side walls 3 and are journaled at theirforward extremities on a. transverse journal shaft 20 carried by theside walls 3'.

The open upper side of the channel12 is adapted to be covered by ahandle 21 shaped to conform to the surrounding structure in which thehousing is mounted. The forward end of the handle 21 is provided withears 22 which extend into the channel 2 and are provided with slots 23to receive the journal shaft 20. The handle is intended to effectpivotal movement of the yoke lever 19, consequently, the ears 22 areprovided with notches 24 which engage the ends of a pin 25 at the sidesof the lever 19.

The ends of the pin 25 are out of engagement with the notches 24 whenthe handle is in its closed position and the slots 23 are raisedrelative to the journal shaft 20. When the handle is raised, the ears 22are guided by the slots 23 so as to direct the notches 24 intoengagement with the pins 25 thereby, on further pivotal movement of thehandle 21, the yoke lever 19 may be pivoted from the position shown inFig. 5 to the position shown in Fig. 6, and in so doing moves the catchmember 8 between its extreme positions. I i

It is desirable that the mechanism within the housing be immobilizedwhen the handle 21 is in its closed position, such as shown in Fig. 5.This is accomplished by means of pairs of stops 26 formed by the ears 22immediately beyond the slots 23. The stops 26 prevent upward movement ofthe yoke lever 19 when the handle is in its closed position. To preventdownward move ment, a pair of set screws 27 mounted in bos'ses28 extendupwardly from the bottom wall 4 of the channel'2. These serve to limitdownward pivotal movementofithe 'yoke lever 19.

2,s94,777 V l The locations of the stops 26 and set screws 27 are suchas to locate the axis of the pin 18 slightly below a plane passingthrough the axes of pins 11 and 20. This is an overcenter position sothat tension applied to the hook 8 tends to turn the yoke lever 19counterclockwise abotu the pin 20, as viewed in Fig. l, so that noupward thrust is applied to the handle lever 21.

The stops 26 may be omitted or relieved to clear the pin 25. Thispermits the set screws to be adjusted so as to predetermine accuratelythe overcenter position of the pin 18.

The extremity of the handle 21 may be secured in its closed position byany suitable fastening element, for example, a pin fastener 29 may bejournaled in the handle member and an aperture provided in a perforatedbracket 30 secured within the channel 2. The margins of the aperture maybe key-slotted to interlock with the pin in a conventional manner.

A spring 31 is interposed between the yoke lever 19 and handle 21 forthe purpose of lifting the handle to a manually accessible position whenthe fastening means is disconnected.

The structure thus far described occupies one component of the preloadlatch. The other component includes a body member 32 which may takevarious forms, depending on the structure in which it is to be mounted.In the drawings the body member 32 is shown as including a top wall 33which may be flush with or submerged below the surface of the structurein which it is mounted. An end wall 34 may conform to the end of suchstructure intended to confront the structure in which the housing 1 ismounted. The side flanges 35 connect the top and end walls.

Formed on the outside of the end wall 34 is a centering boss 36 taperedto mate with the centering aperture 7, as shown best in Fig. 5. Thecentering boss 36 is provided with a clearance bore 37 and isintersected by a transverse bore 38. Oscillatably mounted in the transverse bore 38 is an anchor bar 39 which is transversely screw-threadedto receive a screw shaft 46 which projects rearwardly from the centeringboss 36 to form a latch bar 41. The rearward extremity of the latch baris bifurcated and equipped with a transversely disposed latch pin 42dimensioned to be engaged by the hook end 9 of the catch member 8.

The end of the screw-threaded shaft 40 within the body member 32 isprovided with opposed fiat sides 43. Mounted within the body member is aleaf spring 44 so disposed as to engage the fiat sides 43, so that theshaft 4% and latch bar 41 tend to maintain a position in which one ofthe flat sides is engaged. The flat sides 43 are oriented with respectto the latch pin 42 so that the latch pin may be readily maintained inproper orientation relative to the hook end 9. The spring 44 alsomaintains the directional position of the latch member to allow forcentering with the aperture when in the withdrawn position.

Operation of the preload latch is as follows:

Several of the latches are commonly used for the connection of twostructures, for example, a nose-piece which is to be attached to theforward end of a fuselage. In such installation, the housing 1 of eachlatch is mounted and secured in the forward end of the fuselage with itsupper surface flush with the surface of the fuselage and the end wall orapron 6 flush with the end of the fuselage. Due to the streamlinedcontour of the fuselage, the apron or end wall 6 is not at right anglesto the outer surface of the housing, but instead forms an obtuse angle.

Correspondingly, the end wall 34 of the body member 32 forms an acuteangle with the top wall 33 so that the end Wall 34 is parallel to theapron 6 when the nose piece of the aircraft is brought into confrontingrelation with the end of the fuselage. The centering apertures '7 andthe centering bosses 36 are so located that when in mating relation thefuselage and nose-piece are in proper relative position,

The latch bars 41 of the several preload latches are capable of limitedpivotal movement so that in bringing the nose-piece into positionrelative to the fuselage they may be readily guided through theapertures 7 into the channels 2. To facilitate further guidance of eachlatch bar 41 into engagement with its catch member 8, the bottom wall ofeach housing 1 may be provided with a cam boss 45, as shown in Figs. 5and 6.

In the course of mounting the nose-piece on the fuselage, the handle 21of each housing 1 is in its raised position, such as shown in Figs. 4and 6. In this position the hook end 9 of each catch member 8 is in anelevated position, permitting free entrance of the corresponding latchbar 41. After the nose-piece has been brought approximately intoposition and the centering bosses 36 have been aligned with thecentering apertures 7, the handle of each preload latch may be moved toits closed position. in doing so, each hook end 9 moves in an arcpassing through the corresponding latch pin 42, so as to engage thelatch pin 42 and draw the latch bar 41 into the channel 2 of the housing1.

The amount of tension applied to the latch bar 41 depends upon theadjustment of the shaft 40. The adjustment is made in increments of halfturns of the latch bar. It is desirable that the preload tension on thelatch bar be sufficient to hold the component structures tightlytogether under the intended conditions of operation. The leverageafforded by the handle 21 and the linkage between the connecting barsand yoke lever 19 is such that a substantial preload tension may beapplied to the latch bar 41 without requiring undue manual force toclose the handle 21.

Inasmuch as any movement of the axis of the pin 18 past the planedefined by the axes of the pins 11 and 29 tends to reduce the preloadtension between the components of the latch, the final position of thepin 18 may be critical. Adjustment of the set screws 27, permittingaccurate location of the pin 18, provides a trim or fine adjustment ofthe preload tension.

While a particular embodiment of this invention has been shown anddescribed, it is not 'mtended to limit the same to the exact details ofthe construction set forth, and it embraces such changes, modifications,and equivalents of the parts and their formation and arrangement as comewithin the purview of the appended claims.

What is claimed is:

1. A preload latch, comprising: a housing defining a channel and havingan end Wall defining a centering aperture; a body member including acentering member adapted to enter said aperture and engage the wallsthereof to dispose said housing and body member in predeterminedalignment; a latch member universally mounted in said body member saidcentering member having a bore adapted to receive loosely said latchmember thereby to permit limited uinversal displacement of said latchmember, said latch member protruding beyond said centering member andguidable through said aperture into the channel of said housing; a catchelement mounted in said housing; and means for moving said catch elementinto and out of engagement with said latch member.

2. A preload latch, comprising: a housing defining a channel and havingan end wall defining a centering aperture; a body member including acentering member adapted to enter said aperture and engage the wallsthereof to dispose said housing and body member in predeterminedalignment; a latch member universally mounted in said body member saidcentering member having a bore adapted to receive loosely said latchmember thereby to permit limited universal displacement of said latchmember, said latch member protruding beyond said centering member andguidable through said aperture into the channel of said housing; a catchelement mounted in said housing; and means for moving said catch element between a laterally offset disengaged position relatively near saidaperture and a latch-engaging position relatively remote from saidaperture, said catch element, in moving from said near to said remoteposition, bemg engageable with said latch to draw said latch undertension into said housing, and said centering aperture and centeringmember into engagement.

3. A preload latch, comprising: a housing defining a channel and havingan end wall defining a centering aperture; a body member including acentering member adapted to enter said aperture and engage the wallsthereof to dispose said housing and body member in predeterminedalignment; a latch member universally mounted in said body member saidcentering member having a bore adapted to receive loosely said latchingmember thereby to permit limited universal displacement of said latchmember, said latch member protruding beyond said centering member andguidable through said aperture into the channel of said housing;yieldable means for biasing said latch member whereby said latch membertends to assume a predetermined position relative to said body member,said aperture being beveled to deflect said latch member therein; cammeans in said housing channel to deflect said latch member into a catchengaging position as said housing and body member are brought together;a catch element mounted in said housing; means for moving said catchelement between a laterally offset disengaged position relatively nearsaid aperture and a latch-engaging position relatively remote from saidaperture, said catch element, in moving from said near to said remoteposition, being engageable with said latch to draw said latch undertension into said housing, and said centering aperture and centeringmember into engagement; and means for adjusting the relative positionsof said catch element and latch to vary the tension applied to saidlatch when said catch is in its remote position.

4. A preload latch, comprising: a housing defining a channel and havingan end Wall defining a centering aperture; means for mounting saidhousing in a structure with the open side of said channel substantiallyflush with a side of said structure and said end wall substantiallyflush with an end of said structure; a body member including a centeringmember adapted to enter said aperture and engage the walls thereof todispose said housing and body member in predetermined alignment; a latchmember universally mounted in said body member said centering memberhaving a bore adapted to receive loosely said latch member thereby topermit limited universal displacement of said latch member, said latchmember protruding beyond said centering member and guidable through saidaperture into the channel of said housing; a catch element mounted insaid housing; a handle movable between a position closing said channeland an angular position; means suspending said catch element formovement between a latch-engaging and a latch-releasing position; andmeans interconnecting said catch element and handle.

5. A preload latch, comprising: a housing defining a channel and havingan end wall defining a centering aperture; a body member including acentering member adapted to enter said aperture and engage the wallsthereof to dispose said housing and body member in predeterminedalignment; a latch member universally mounted in said body member saidcentering member having a bore adapted to receive loosely said latchingmember thereby to permit limited universal displacement of said latchmember, said latch member protruding beyond said centering member andguidable through said aperture into the channel of said housing;yieldable means for biasing said latch member whereby said latch membertends to assume a predetermined position relative to said body member,said aperture being beveled to deflect said latch member therein; cammeans in said housing channel to deflect said latch member into a catchengaging position as said housing and body member are brought together;a catch element mounted in said housing; and means for moving said catchelement to and from said aperture and to pivot said catch elementlaterally in the region of its movement nearest said aperture to clearsaid latch member.

6. A preload latch, comprising: a housing defining a channel and havingan end Wall defining a centering aperture; a body member including acentering member adapted to enter said aperture and engage the wallsthereof to dispose said housing and body member in predeterminedalignment; a latch member universally mounted in said body member saidcentering member having a bore adapted to receive loosely said latchmember thereby to permit limited universal displacement of said latchmember, said latch member protruding beyond said centering member andguidable through said aperture into the channel of said housing; a catchelement mounted in said housing; means for moving said catch element toand from said aperture and to pivot said catch element laterally in theregion of its movement nearest said aperture to clear said latch member;and means for adjusting the elfective length of said latch member tovary the tension load imposed thereon by said catch element.

7. A preload latch, comprising: a housing defining a channel and havingan end wall defining a centering aperture; a body member including acentering member adapted to enter said aperture and engage the wallsthereof to dispose said housing and body member in predeterminedalignment; a latch member universally mounted in said body member saidcentering member having a bore adapted to receive loosely said latchmember thereby to permit limited universal displacement of said latchmember, said latch member protruding beyond said centering member andguidable through said aperture into the channel of said housing; a catchelement mounted in said housing; link and lever means for moving saidcatch element to and from said aperture, said means exerting maximumleverage as said catch element is moved in the region remote from saidaperture thereby to apply tension to said latch member, said means alsobeing operative to move said catch element laterally of said latchmember as said catch element is moved in the region nearest saidaperture; and means for adjusting the effective length of said latchmember to vary the tension load imposed thereon by said catch element.

References Cited in the file of this patent UNITED STATES PATENTS2,710,214 Summers June 7, 1955 2,712,955 Andrews July 12, 1955

